158 ELEMENTARY PROPERTIES 



distant from this earth, the rays which issue 

 from the sun reach the surface here below, in 

 the short space of 8 minutes, llg seconds of 

 time ; a distance which could not be traversed 

 by the swiftest ball that was ever fired out of 

 the largest cannon, in less time than thirty-two 

 years ; admitting, what is impossible, that it 

 continues to preserve its initial velocity of one 

 mile per second of time. 



If the solar rays possessed a correspondent 

 degree of density or of motive power, the com- 

 bined effect the momentum, (i. e. the quantity 

 and velocity compounded together,) would pro- 

 duce an impulse which would be capable of 

 overcoming the resistance which could be op- 

 posed to them by the densest and hardest 

 matter, existing in the system of nature. The 

 eyes of animated beings, in particular, to whose 

 use the solar rays are more especially designed 

 to subserve, would be torn asunder, and totally 

 disorganised; for, as Mr. NICHOLSON very 

 justly observes, that the momentum of a body 

 is, as its mass multiplied by its velocity, and 

 as the solar rays were in the excess of 200,000 

 to 1 to a cannon ball, it must follow, that, if the 

 particles of light were equal, in mass, to the 

 two-millionth part of the smallest grain of sand, 

 we should be no more able to endure their 

 impulse, than of the sand when shot point- 

 blank from a cannon. In illustration of the 



